Upgrades
100 amp vs 200 amp: does your Toronto home need a service upgrade?
A 100 amp service runs plenty of Toronto homes without trouble. Add a car charger, a heat pump or a basement apartment, though, and the numbers change fast. Here's how to tell where your house stands.
What's the difference between 100 amp and 200 amp service?
The amp rating is the most current your electrical service can deliver at one time. A 200 amp service can carry twice the load of a 100 amp one. It doesn't mean you use twice the power. It means you have twice the room before the main breaker steps in.
The service is a chain of parts, not just the panel. It runs from the utility's connection point, through the mast or underground entry, the meter base and the main cable, to the main breaker. Every link is sized for a rating, and the smallest one sets the limit.
So is 200 amp better than 100 amp? Only if you need the headroom. A bigger service won't make lights brighter or appliances run better. It lets more large loads run at once without tripping the main or overloading the supply.
How to tell if you have 100 amp or 200 amp service
Start with the main breaker. It's usually the large breaker at the top of the panel, set apart from the rest, with a number stamped on the handle. That number is normally the size of your service.
Older homes may have a fuse box instead, with a main switch or cartridge fuses. A label inside the panel door also lists the panel's rating. Don't remove the panel cover to look further; the parts behind it are live.
One catch: the panel rating and the service size aren't always the same. A panel rated for 200 amps can sit behind a 100 amp main breaker and a 100 amp service cable. The meter base and the cable from the street matter just as much. A photo of the open panel and the meter usually tells us which you have.
Is 100 amp service enough for your home?
For many houses, yes. A home of modest size with gas heat, a gas range and a gas water heater can live comfortably on 100 amps. Central air and a dryer usually fit too, as long as nothing else large is added.
The trouble starts when gas appliances are swapped for electric ones, or when a big new load arrives. Each of those moves a large, steady demand onto the electrical service. Two or three of them together usually push a 100 amp house past what it can safely carry.
| Load | On a 100 amp service | Why |
|---|---|---|
| Gas furnace, range and water heater | Usually fine | The heavy energy use is on gas, not electricity |
| Central air conditioning | Usually fine on its own | A large load, but it runs mainly in summer |
| Level 2 EV charger | Often tight | It draws heavily for hours, often in the evening |
| Heat pump with electric backup heat | Often too much | Backup heat strips are among the largest loads in a house |
| Induction range | Depends on the rest | A big load when several elements run at once |
| Basement suite with its own kitchen | Usually too much | Two households' cooking, laundry and heat on one service |
The table is a rough guide, not a verdict. A load calculation on your actual house is what decides it.
Signs you need more capacity
Some signs come from what you're planning. Others come from how the house behaves today.
You're adding a big load
An EV charger, a heat pump, an induction cooktop, a hot tub or a second suite is on the list.
The main breaker trips
Not a single circuit, but the main. That's the service telling you it's at its limit.
Lights dim when things start
A noticeable dip when the air conditioner or dryer kicks in can point to a stretched service.
The panel is full
Every space is used, and newer circuits have been doubled up to fit.
You still have fuses
A fuse panel is usually 60 or 100 amps and is often flagged by insurers.
Visible wear
Rust, scorch marks, a warm cover or a buzzing sound at the panel need a look regardless of size.
A main breaker that trips, scorch marks or a buzzing panel are reasons to call now, not to plan for later.
How a load calculation settles the question
A load calculation is the method the electrical code sets out for working out a home's demand. It starts from the floor area. Then it adds the fixed loads: heating, cooling, cooking, water heating, laundry, and any charger, pool or hot tub.
The code doesn't assume everything runs at once, and it doesn't ignore the big loads either. The result is a number in amps that the service has to carry. Compare that with your service size, and the decision is mostly made for you.
We do the calculation with your plans in it, not just what's in the house now. If you expect a car charger next year and a heat pump in five, both go in. Sizing once costs less than upgrading twice. Our page on permits and load calculations explains how it feeds the permit.
What's required to upgrade from 100 amp to 200 amp
Can you convert 100 amp to 200 amp by swapping the main breaker? No. The main breaker protects the cable and parts behind it, and those were sized for 100 amps. A bigger breaker on a 100 amp cable is a fire risk.
A real 100 amp to 200 amp upgrade replaces the whole service chain. That usually includes:
- A new mast or service entry rated for 200 amps, or work on the underground cable where it enters the house.
- A new meter base sized for the larger service.
- New main service cable from the meter base to the panel.
- Grounding and bonding brought up to current requirements.
- A 200 amp panel, with existing circuits reconnected and labelled.
On top of the work itself, there's the ESA permit and the utility side. Our panel upgrade service covers all of it in one written price.
Toronto Hydro, Alectra and Hydro One: the utility's part
Your utility owns the meter and the supply up to your house. Only the utility can disconnect it safely, so every service upgrade includes a booked disconnect and reconnect. We arrange that booking as part of the job.
Which utility you deal with depends on where you live. The City of Toronto is served by Toronto Hydro. Much of Peel and York Region, including Mississauga, Brampton, Vaughan and Markham, is served by Alectra Utilities. Hydro One serves more rural areas such as Caledon and King. A few towns have their own, such as Oakville Hydro and Newmarket-Tay Power Distribution.
When the service size goes up, the utility reviews the request. It decides whether its own line or transformer needs work, and it sets the timing. Each utility has its own forms and charges, so we confirm them for your address in the quote. For the Toronto steps in detail, read our guide to a service upgrade with Toronto Hydro.
Alternatives to a full service upgrade
A bigger service isn't the only answer. Where the load calculation shows you're close but not over, other options may work:
- Load management. Approved devices can watch the house's demand and pause a car charger when other loads peak. Charging carries on once demand drops.
- Sizing the new load sensibly. A charger set to a lower current can still cover typical daily driving overnight, with less strain on the service.
These work in the right house and fall short in the wrong one. A heat pump with backup heat, or a full second suite, usually needs the capacity itself. We'll tell you plainly which side of that line you're on.
What affects the cost of going to 200 amps
We don't publish prices, because two upgrades on one street can be very different jobs. Overhead or underground service, the condition of the mast and meter base, grounding, and whether the panel has to move all change the scope.
We explain each of those factors in our guide to what decides the cost of a panel upgrade. You get a fixed, written price after a site visit.
Quick answers about 100 and 200 amp service
Should I upgrade to 200 amp service during a renovation? If the renovation adds big loads, usually yes. Walls are open, the electrician is already on site and the panel can be placed where it works best.
Is 100 amp or 200 amp service right for a detached garage? The garage is usually fed by a sub-panel from the house, sized for the garage's own loads. A workshop or charger there still counts against the main service, so the house calculation comes first.
What about a 60 amp service in Ontario? Sixty amps is very little for a modern household, and many insurers ask about it. A 60 amp home that's adding anything large is usually a candidate for 200 amps.
Will a bigger service raise my hydro bill? Your bill is driven mainly by the energy you use, not by the size of the service behind it.
How long is the power off? Usually most of one day. The utility disconnects in the morning, and power comes back once the work is ready and approved.
Finding out where your home stands
Send us two photos: the panel with its door open, and the meter outside. That's often enough to tell you your current service size and whether an upgrade is likely. A site visit and load calculation then give you a firm answer and a fixed price.
Every upgrade is led by a Master Electrician and covered by our 1-year workmanship warranty. If you're in North York, start with our North York panel upgrade page. Elsewhere in Toronto, see panel upgrades in Toronto.
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